Build for only one target for docs.rs (#5427)

* Add docs.rs metadata to all cargo.toml files

* Remove docs.rs metada in substrate's cargo.toml

substrate/client/executor/Cargo.toml

@@ -52,3 +52,6 @@ wasmtime = [
 wasmi-errno = [
 	"wasmi/errno"
 ]
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]

substrate/client/executor/common/Cargo.toml

@@ -22,3 +22,6 @@ sp-serializer = { version = "2.0.0-alpha.5", path = "../../../primitives/seriali
 
 [features]
 default = []
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]

substrate/client/executor/runtime-test/Cargo.toml

@@ -28,3 +28,6 @@ std = [
 	"sp-std/std",
 	"sp-allocator/std",
 ]
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]

substrate/client/executor/wasmi/Cargo.toml

@@ -19,3 +19,6 @@ sp-wasm-interface = { version = "2.0.0-alpha.5", path = "../../../primitives/was
 sp-runtime-interface = { version = "2.0.0-alpha.5", path = "../../../primitives/runtime-interface" }
 sp-core = { version = "2.0.0-alpha.5", path = "../../../primitives/core" }
 sp-allocator = { version = "2.0.0-alpha.5", path = "../../../primitives/allocator" }
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]

substrate/client/executor/wasmtime/Cargo.toml

@@ -22,3 +22,6 @@ wasmtime = { package = "substrate-wasmtime", version = "0.13.0-threadsafe.1" }
 
 [dev-dependencies]
 assert_matches = "1.3.0"
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]